8. In 2009, U. S. families, on average, spent $541.25 on back-to-school supplies. In 2016, the figure rose to $681.25.

a. Find a linear model in the form, y=mx+b, that fits this data using x=0 to stand for
the year 2000.

b. Use your model or perhaps another algebraic idea to predict the back-to-school cost in
the 2005